This was not confined to the north but may occur on the mountains of England and Wales: Salix herbacea, Silene acaulis and Dryas octopetala will serve as examples.
The following circumpolar species are common, and widely diffused throughout the whole of the Alps: Silene acaulis, Dryas octopetala, Saxifraga oppositifolia, S.
With the melting of the great ice-sheet the climate became milder, and the southern part of Sweden was covered with shrubs and plants now found only in the northern and alpine parts of the country (Salix polaris, Dryas octopetala, Betula nana, &c.).
Of Phanerogams, only the Dryas octopetala covers small areas of the debris, interspersed with isolated Cochlearia, &c., and, where a layer of thinner clay has been deposited in sheltered places, the surface is covered with saxifrages, &c.; and a carpet of mosses allows the arctic willow (Salix polaris) to develop. Where a thin sheet of humus, fertilized by lemmings, has accumulated, a few flowering plants appear, but even so their brilliant flowers spring direct from the soil, concealing the developed leaflets, while their horizontally spread roots grow out of proportion; only the Salix lanata rises to 7 or 8 in., sending out roots I in.